In recent years, following the improvement of hardware performance, the use of three-dimensional computer graphics (also referred to as “3D CG” (Three Dimensional Computer Graphics), or referred to simply as “CG” (Computer Graphics) or the like) has been gaining popularity. Also, various data structures for representing characters in 3D CG (CG models) have been proposed. For example, data structures that are suitable for characters having complex skeleton structures such as human beings have been proposed (see, for example, patent literature 1 and 2). By using such CG models and data structures, CG animation movies can be made.